Reversible controlled switching of photocatalysis for microorganism protection in the coupling of photocatalysis and biodegradation

The coupling of photocatalysis and biodegradation (CPB) has shown great potential as a low-cost, environmental friendly and sustainable wastewater treatment technology. However, the photo-generated reactive oxidative species (ROS) could attack microorganisms in the CPB. Here, a photo-controlled reversible photocatalytic system was developed for protecting microorganisms from ROS attack in CPB. Thermal-responsive polymer (TRP) was coated on the surface of yolk-shell [email protected]2, and then [email protected]2 @TRP was attached to the surface of graphene (photo-thermal converter) to form the photo controlled reversible photocatalytic system (RPS). Without light irradiation, the soluble contaminants could be absorbed into the void space of [email protected]2 @TRP. And under light irradiation, the photo-generated ROS would be locked inside the silica shell to degrade the absorbed organic molecules, avoiding harming microorganisms in CPB. Batch results showed that this CPB system could simultaneously remove 97.24 % of phenol (model contaminant) and 91.12 % of TOC under intermittent light irradiation, which was superior to other control groups. This work provides a new strategy to protect microorganisms in CPB for effective wastewater treatment.